<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="vue.js"></script>
</head>
<style>
    .custom-appear-active{
        /*color: red;*/
        background: red;
        transition: all 2s ease;
    }
    .custom-appear{
        font-size: 40px;
        /*color: #e069e2;*/
        background: blue;
    }
    .custom-appear-to{
        /*color: #e29138;*/
        background: burlywood;
    }
</style>
<body>
<!--
         关于appear的用法和enter的用法相似，它只是在第一次渲染的时候才会起作用。看完整的代码：
    但是这里有一些问题：关于appear-class、 appear-to-class、 appear-active-class的相同属性那个起作用的问题。
    四种情况：（与他们在style中的排列顺序有关系）
    1、appear-class、 appear-to-class、 appear-active-class或者 appear-to-class、appear-class、 appear-active-class的排列顺序，此时只有appear-active-class的属性起作用。
    2、appear-active-class、appear-class、 appear-to-class
    此时appear-active-class的不起作用，由appear-class过渡到appear-to-class属性。
    3、appear-class、appear-active-class、 appear-to-class
    此时appear-class属性不起作用，由appear-active-class过渡到 appear-to-class属性。
    4、 appear-to-class、 appear-active-class、appear-class
    此时appear-to-class不起作用，由appear-class过渡到 appear-active-class属性。
    enter也有相似的问题
 -->
<div id="app">
    <transition
            appear
            appear-class="custom-appear"
            appear-to-class="custom-appear-to"
            appear-active-class="custom-appear-active"
    >
        <p>appear</p>
    </transition>
</div>
<script>

    new Vue({
        el: "#app"
    })
</script>
</body>
</html>